Three-Dimensional Printing Processes Using 1,1-Di-Activated Vinyl Compounds

ABSTRACT

A process for producing an article by three-dimensional printing includes applying a 1,1-di-activated vinyl compound-containing liquid binder over a predetermined area of a layer of solid particles. The liquid binder infiltrates gaps between the solid particles to form a first cross-sectional layer of an article, and the 1,1-di-activated vinyl compound reacts to solidify the liquid binder and bind the solid particles in the first cross-sectional layer of the article. Also provided is an article produced by the three-dimensional printing process, set forth herein.

BACKGROUND OF THE INVENTION

Three-dimensional printing, also known as additive manufacturing orrapid prototyping, involves the production of three-dimensional articlesby synthesizing successive layers of solid material that collectivelybond together to form the articles. Various types of three-dimensionalprinting processes and equipment for building an article layer-by-layerhave been developed. Examples of three-dimensional printing processesinclude stereolithography/photopolymerization, selective lasersintering, electron beam melting, extrusion deposition, and particlebinding with liquid binders delivered using inkjet-like printer nozzles(the “liquid binder method”). Three-dimensional printing processes andequipment are typically computer-controlled, which facilitates thedirect production of articles from computer-aided design (CAD) models.

SUMMARY OF THE INVENTION

The invention described in this specification generally relates tomaterials and methods for the three-dimensional printing of articles.

A process for producing an article by three-dimensional printingcomprises positioning a layer of solid particles in a planar bed. Aliquid binder is applied over a predetermined area of the layer of solidparticles. The liquid binder comprises a 1,1-di-activated vinylcompound, or a multifunctional form thereof, or a combination thereof.The gaps between the solid particles are infiltrated with the liquidbinder in the predetermined area of the layer of solid particles to forma first cross-sectional layer of an article. The 1,1-di-activated vinylcompound, or multifunctional form thereof, or combination thereof, isreacted to solidify the liquid binder and bind the solid particles inthe first cross-sectional layer of the article.

A three-dimensional article comprises a plurality of cross-sectionallayers bonded together. Each cross-sectional layer comprises a solidbinder comprising a reaction product of a 1,1-di-activated vinylcompound, or a multifunctional form thereof, or a combination thereof. Aplurality of solid particles are embedded in the solid binder.

It is understood that the invention described in this specification isnot necessarily limited to the examples summarized in this Summary.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features and characteristics of the invention described in thisspecification may be better understood by reference to the accompanyingfigures, in which:

FIG. 1A is a cross-sectional schematic diagram in perspective viewshowing a layer of solid particles in a stationary planar bed;

FIG. 1B is a cross-sectional schematic diagram in perspective viewshowing the application of a liquid binder over a predetermined area ofthe layer of solid particles shown in FIG. 1A, and the infiltration ofthe gaps between the solid particles with the liquid binder in thepredetermined area to form a first cross-sectional layer of an article;

FIG. 1C is a cross-sectional schematic diagram in perspective viewshowing (i) the positioning of a second layer of solid particles overthe first cross-sectional layer of the article shown in FIG. 1B, (ii)the application of additional liquid binder over a predetermined area ofthe second layer of solid particles, and (iii) the infiltration of thegaps between the solid particles with the additional liquid binder inthe predetermined area of the second layer of solid particles to form asecond cross-sectional layer of an article, wherein the secondcross-sectional layer of the article is located over and in physicalcontact with the first cross-sectional layer of the article;

FIG. 1D is a cross-sectional schematic diagram in perspective viewshowing (i) the positioning of a third layer of solid particles over thesecond cross-sectional layer of the article shown in FIG. 1C, (ii) theapplication of additional liquid binder over a predetermined area of thethird layer of solid particles, and (iii) the infiltration of the gapsbetween the solid particles with the additional liquid binder in thepredetermined area of the third layer of solid particles to form a thirdcross-sectional layer of an article, wherein the third cross-sectionallayer of the article is located over and in physical contact with thesecond cross-sectional layer of the article;

FIGS. 2A and 2B are schematic diagrams in perspective view of thethree-dimensional printed article produced in accordance with theexamples shown in FIGS. 1A-1D and 3A-3D;

FIG. 3A is a cross-sectional schematic diagram in perspective viewshowing a layer of solid particles in a moveable planar bed configuredfor vertical movement relative to a printing nozzle (not shown);

FIG. 3B is a cross-sectional schematic diagram in perspective viewshowing the application of a liquid binder over a predetermined area ofthe layer of solid particles shown in FIG. 3A, and the infiltration ofthe gaps between the solid particles with the liquid binder in thepredetermined area to form a first cross-sectional layer of an article;

FIG. 3C is a cross-sectional schematic diagram in perspective viewshowing (i) elevational movement of the planar bed, (ii) the positioningof a second layer of solid particles over the first cross-sectionallayer of the article shown in FIG. 3B, (iii) the application ofadditional liquid binder over a predetermined area of the second layerof solid particles, and (iv) the infiltration of the gaps between thesolid particles with the additional liquid binder in the predeterminedarea of the second layer of solid particles to form a secondcross-sectional layer of an article, wherein the second cross-sectionallayer of the article is located over and in physical contact with thefirst cross-sectional layer of the article; and

FIG. 3D is a cross-sectional schematic diagram in perspective viewshowing (i) elevational movement of the planar bed, (ii) the positioningof a third layer of solid particles over the second cross-sectionallayer of the article shown in FIG. 3C, (iii) the application ofadditional liquid binder over a predetermined area of the third layer ofsolid particles, and (iv) the infiltration of the gaps between the solidparticles with the additional liquid binder in the predetermined area ofthe third layer of solid particles to form a third cross-sectional layerof an article, wherein the third cross-sectional layer of the article islocated over and in physical contact with the second cross-sectionallayer of the article.

The reader will appreciate the foregoing features and characteristics,as well as others, upon considering the following detailed descriptionof the invention according to this specification.

DETAILED DESCRIPTION OF THE INVENTION

As used in this specification, particularly in connection with coatings,layers, or films, the terms “on,” “onto,” “over,” and variants thereof(e.g., “applied over,” “formed over,” “deposited over,” “provided over,”“located over,” and the like), mean applied, formed, deposited,provided, or otherwise located over a surface of a substrate or a powderbed, but not necessarily in contact with the surface of the substrate orpowder bed, unless explicitly stated so. For example, a coating layer“applied over” a substrate does not preclude the presence of one or moreother coating layers of the same or different composition locatedbetween the applied coating layer and the substrate. Likewise, a secondcoating layer “applied over” a first coating layer does not preclude thepresence of one or more other coating layers of the same or differentcomposition located between the applied second coating layer and theapplied first coating layer.

As used in this specification, the terms “polymer” and “polymeric” meansprepolymers, oligomers, and both homopolymers and copolymers. As used inthis specification, “prepolymer” means a polymer precursor capable offurther reactions or polymerization by one or more reactive groups toform a higher molecular mass or cross-linked state.

As used in this specification, the term “1,1-di-activated vinylcompound” means a compound comprising a vinyl group having two electronwithdrawing groups (EWG) covalently bonded to one of the π-bondedcarbons and no substituents covalently bonded to the other π-bondedcarbon (i.e., -EWG-C(═CH₂)-EWG-), wherein the electron withdrawinggroups independently comprise halogen groups, haloalkyl groups,carbonyl-containing groups (e.g., esters, amides, aldehydes, ketones,acyl halides, carboxylic/carboxylate groups), cyano groups, sulfonategroups, ammonium groups, quaternary amine groups, or nitro groups. Theterm “multifunctional form” means a compound comprising two or more1,1-di-activated vinyl groups covalently bonded in one molecule. Forinstance, a dialkyl methylene malonate is an example of a1,1-di-activated vinyl compound, and a transesterification adduct of adialkyl methylene malonate and a polyol is an example of amultifunctional form of a dialkyl methylene malonate.

The present invention is directed to materials and methods for thethree-dimensional printing of articles. In the liquid binder method ofthree-dimensional printing, an inkjet-like printing nozzle delivers aliquid binder (or a solution of binder or a dispersion of binderparticles in a liquid solvent or other volatile carrier) onto layers ofsolid particles (powders) in a cross-sectional pattern. The liquidbinder infiltrates into the gaps between the particles of the powdermaterial, wets out the particles, and hardens (e.g., solidifies bypolymerization, chemical crosslinking, or solidification of moltenbinder), thereby bonding the powder material into a solidified layer inthe shape of the cross-sectional pattern. After the firstcross-sectional portion is formed, the previous steps are repeated,building successive cross-sectional portions until the final article isformed comprising the solid particles embedded in the solidified binder.The solidified binder also bonds each cross-sectional layer to theprevious layer, thereby building up a monolithic and integralthree-dimensional article in a layer-by-layer fashion.

FIGS. 1A-1D show a process for producing an article by three-dimensionalprinting. Referring to FIG. 1A, a layer of solid particles 10 ispositioned in a planar bed 12 in a container 14. As used in thisspecification, the term “layer of solid particles” means a collection ofsolid particles forming a bed. A layer of solid particles can have anythickness, provided that a liquid binder can infiltrate into the gapsbetween the collection of solid particles and through the thickness ofthe layer of solid particles. The layer of solid particles 10 comprisespowder or other collection of particulate materials, which can bepresent in a loose and free-flowable form (i.e., un-compacted) or in acompacted density. The layer of solid particles 10 can be positioned inthe planar bed 12 in the container 14 using any suitable applicationtechniques and equipment (not shown), such as, for example,pneumatically-operated or gravity-driven powder dispensers, whichdispense a uniform layer of powder as they travels across the planar bed12 (see, e.g., U.S. Pat. Nos. 7,828,022 B2; 6,672,343 B1; and U.S.Patent Publication No. 2010/0272519 A1, which are incorporated byreference into this specification).

Additional powder spreading techniques and equipment include, forexample, a spreading blade, which is at least as long as the width ofthe planar bed 12, and wipes across the surface of the planar bed 12 tospread out powder deposited by a powder dispenser (see, e.g., U.S. Pat.Nos. 5,387,380 and 6,799,959 B1, which are incorporated by referenceinto this specification), and a counter-rotating roller, which is atleast as long as the width of the planar bed 12, and traverses acrossthe surface of the planar bed to spread out powder that is deposited bya powder dispenser (see, e.g., U.S. Pat. No. 5,597,589; U.S. PatentPublication No. 2001/0050448 A1; and U.S. Pat. No. 8,568,124 B2, whichare incorporated by reference into this specification). The layer ofsolid particles 10 can be positioned in the planar bed 12 in thecontainer 14 by spreading a powder comprising the solid particles usinga counter-rotating roller that rotates in a direction opposite to thatwhich the roller would rotate if it were simply being rolled across thesurface of the planar bed 12. Such “counter-rotating” roller powderspreaders have been found to give superior results to blade powderspreaders because the rotating action of the roller picks up andredistributes the dispensed powder in front of the roller as it isencountered instead of just pushing the powder pile, thus betterovercoming the distribution disparities of the as-deposited powder. Therotation action at the trailing side of the roller provides a consistentgentle compaction of the powder material and is less likely to disruptthe location or damage underlying cross-sectional layers that previouslyreceived binder.

The layer of solid particles 10 can be positioned in the planar bed 12with a suitable thickness to form an individual constituent layer usedto build-up three-dimensional articles in a layer-by-layer fashion. Thelayer of solid particles 10 can have a thickness ranging from 10 μm to1000 μm, or any sub-range subsumed therein, such as, for example, 25-500μm, 50-250 μm, 80-180 μm, or 100-150 μm. In practice, the thickness ofthe layer of solid particles is limited, in part, by the amount ofliquid binder that can be delivered to the layer, as described below.

Referring to FIG. 1B, a liquid binder 20 is applied over a predeterminedarea 23 of the layer of solid particles 10 in the planar bed 12 in thecontainer 14. The liquid binder 20 comprises a 1,1-di-activated vinylcompound, or a multifunctional form thereof, or a combination thereof,as described below. The liquid binder 20 infiltrates the gaps betweenthe solid particles in the predetermined area 23 of the layer of solidparticles 10, wets out the solid particles, and forms a firstcross-sectional layer 30 of an article. The 1,1-di-activated vinylcompound, or multifunctional form thereof, or combination thereof, inthe liquid binder 20 reacts, as described below, and solidifies theliquid binder 20, which binds together the solid particles in the firstcross-sectional layer 30.

The liquid binder 20 is applied over the predetermined area 23 of thelayer of solid particles 10 using a suitable nozzle 80. The nozzle 80can be computer-controlled and have six translationaldegrees-of-freedom, as indicated at 85—i.e., the nozzle 80 can move inthe X and Y directions parallel to the planar bed 12 to apply the liquidbinder 20 in the predetermined area 23, and the nozzle 80 can move inthe Z direction perpendicular to the planar bed 12 to position thenozzle 80 closer to or farther away from the planar surface of the layerof solid particles 10. The ability to move in the Z directionperpendicular to the planar bed 12 also allows the nozzle to accommodatethe positioning of additional layers of solid particles over the firstlayer 10, as described below, while maintaining a controlled distancerelative to the planar surface of the layer of solid particles 10.

Although not shown in FIGS. 1B-1C, it is understood that implementationsof the processes described in this specification can utilize two or morenozzles to apply the liquid binder 20 in the predetermined area 23 (forexample, an inkjet-like print head comprising multiple nozzles). It maybe desirable to produce three-dimensional printed articles comprisingrelative small structural features. The size of the structural featuresthat can be produced is determined, in part, by the size of the dropletsdispensed from the nozzle 80 (or multiple nozzles, if employed). Ingeneral, smaller nozzles produce smaller droplets and smaller structuralfeatures. However, smaller nozzles reduce the printing speed because thevolume of liquid binder applied onto the layer of solid particles 10.The size of the nozzle 80 (or multiple nozzles, if employed) and theresulting droplets of liquid binder applied onto the layer of solidparticles 10 may be practically limited by the dimensional tolerancesand the acceptable amount of distortion in the final three-dimensionalarticle.

A process for producing an article by three-dimensional printing canfurther comprise repeating the powder/particle-positioning, liquidbinder application, infiltration, and reaction steps, as describedherein, a plurality of times to produce a plurality of bondedcross-sectional layers that together comprise the three-dimensionalarticle. Referring to FIG. 1C, the nozzle 80 is moved upwardly (alongthe Z-axis) away from the surface of the first layer of solid particles10 and the first cross-sectional layer 30 of the three-dimensionalarticle being printed. A second layer of solid particles 40 ispositioned over the first layer of solid particles 10 and over the firstcross-sectional layer 30 of the article. Additional liquid binder 20 isapplied over a predetermined area 25 of the second layer of solidparticles 40 in the planar bed 12 in the container 14. The liquid binder20 comprises a 1,1-di-activated vinyl compound, or a multifunctionalform thereof, or a combination thereof, as described below. The liquidbinder 20 infiltrates the gaps between the solid particles in thepredetermined area 25 of the second layer of solid particles 40, wetsout the solid particles, and forms a second cross-sectional layer 50 ofthe article. The second cross-sectional layer 50 is located over and inphysical contact with the first cross-sectional layer 30 of the article.The 1,1-di-activated vinyl compound, or multifunctional form thereof, orcombination thereof, in the liquid binder 20 reacts, as described below,and solidifies the liquid binder 20, which binds together the solidparticles in the second cross-sectional layer 50, and also bindstogether the first cross-sectional layer 30 and the secondcross-sectional layer 50.

Referring to FIG. 1D, the nozzle 80 is again moved upwardly (along theZ-axis) away from the surface of the second layer of solid particles 40and the second cross-sectional layer 50 of the three-dimensional articlebeing printed. A third layer of solid particles 60 is positioned overthe second layer of solid particles 40 and over the secondcross-sectional layer 50 of the article. Additional liquid binder 20 isapplied over a predetermined area 27 of the third layer of solidparticles 60 in the planar bed 12 in the container 14. The liquid binder20 comprises a 1,1-di-activated vinyl compound, or a multifunctionalform thereof, or a combination thereof, as described below. The liquidbinder 20 infiltrates the gaps between the solid particles in thepredetermined area 27 of the third layer of solid particles 60, wets outthe solid particles, and forms a third cross-sectional layer 70 of thearticle. The third cross-sectional layer 70 is located over and inphysical contact with the second cross-sectional layer 50 of thearticle. The 1,1-di-activated vinyl compound, or multifunctional formthereof, or combination thereof, in the liquid binder 20 reacts, asdescribed below, and solidifies the liquid binder 20, which bindstogether the solid particles in the third cross-sectional layer 70, andalso binds together the second cross-sectional layer 50 and the thirdcross-sectional layer 70.

As described, the powder/particle-positioning, liquid binderapplication, infiltration, and reaction steps can be repeated aplurality of times to produce a plurality of bonded cross-sectionallayers that together comprise the three-dimensional article. The liquidbinder can be applied in any predetermined two-dimensional pattern(circular, in the figures, for purposes of illustration only) to producethe constituent cross-sectional layers using any suitable mechanism,such as a Drop-On-Demand printhead driven by customized software whichreceives data from a CAD system. The hardening/curing reaction of the1,1-di-activated vinyl compound produces solidified and relatively rigidcross-sectional portions of the final three-dimensional article.Maximizing the amount of liquid binder applied onto and infiltrated intothe cross-sectional layers can ensure that sufficient binder isavailable to bond together the solid particles within each layer andalso to bond together each adjacent layer into a monolithic and integralthree-dimensional article.

For optimal adherence and/or bonding between the constituentcross-sectional layers, any given cross-sectional layer should maintainan at least partially unhardened or unsolidified state at the time thesubsequent cross-sectional layer is applied onto that layer. Thisresults in relatively simultaneous solidification and integration ofadjacent cross-sectional layers where the respective layers contact eachother. A less optimal bond may form between constituent layers wheresolidification of a preceding layer is complete before application of asubsequent layer.

The predetermined two-dimensional pattern or cross-sectional shape of alayer can be the same or different from that of an adjacent layer, orany other layer. It is understood, however, that in order to form amonolithic and integral three-dimensional article, at least a portion ofeach constituent cross-sectional layer must physically contact and bondto at least a portion of an adjacent constituent cross-sectional layeror layers. The two-dimensional pattern (i.e., the predetermined area)for each constituent cross-sectional layer can be inputted from acomputer that controls the motion and binder output rate of the printingnozzle or nozzles. In such examples, the accumulation of the perimetercontours of each constituent cross-sectional layer represents the outersurface of the three-dimensional article as modeled in computer memoryusing CAD software.

Referring again to FIGS. 1A-1D, any unhardened or unsolidifiedparticulate material in the planar bed 12 that was not exposed to theliquid binder 20 remains loose and free-flowing. The unhardened orunsolidified particulate material is left in place in the planar bed 12until formation of the final three-dimensional article is complete.Leaving the unhardened or unsolidified particulate material in placeensures that the article is mechanically supported during production,allowing features such as overhangs, undercuts, and cavities (not shown)to be defined without using separate support structures.

Referring again to FIG. 1D, at the end of a three-dimensional printingprocess, after the final article is completely formed, only the topsurface of the final article is visible in the container 14. The finalarticle is otherwise immersed in the planar bed 12 of loose (unhardenedor unsolidified) particulate material that did not contact the liquidbinder 20. FIGS. 2A and 2B are schematic diagrams of the finalthree-dimensional article 90 produced by the process illustrated inFIGS. 1A-1D. The article 90 is a monolithic and integralthree-dimensional article comprising a plurality of cross-sectionallayers (30, 50, and 70) bonded together. Each cross-sectional layercomprises solid binder comprising a reaction product of a1,1-di-activated vinyl compound, or a multifunctional form thereof, or acombination thereof, and a plurality of solid particles embedded in thesolid binder.

After removal of the three-dimensional article 90 from the planar bed12, loose particulate material can be removed, for example, by airblowing, and the article 90 can undergo post-processing treatments suchas, for example, cleaning, infiltration with stabilizing materials, andcoating. For example, the three-dimensional article 90 in the as-printedstate, although monolithic and integral, can nevertheless be relativelyporous. The article 90 can therefore be infiltrated and/or coated with avariety of materials to improve the article's hardness, strength,toughness, surface properties, or any combination thereof. Infiltratingmaterials and/or coatings can fill in any pores in the article 90,thereby improving the article's surface finish, and making the article90 more water-resistant and/or organic solvent-resistant. Suitableinfiltrating materials and coatings include, for example, molten waxes,polyurethane-based coatings, acrylic-based coatings, and epoxy-basedcoatings.

A three-dimensional article formed using the materials, systems, andprocesses described in this specification comprise a plurality ofdistributed layers of the mixture of the solid particles and thesolidified binder. The layers can each independently have a thickness inthe range of thickness ranging from 10 μm to 1000 μm, or any sub-rangesubsumed therein, such as, for example, 25-500 μm, 50-250 μm, 80-180 μm,or 100-150 μm. The two-dimensional faces of the constituentcross-sectional layers stack and bond together, and the final shape ofthe three-dimensional article is defined by the collective contours ofeach of the constituent cross-sectional layers. The viewable surface ofthe three-dimensional printed article thus comprises layer edges only,except for the faces of the uppermost and lowermost layers.

The process illustrated in FIGS. 1A-1D produces a three-dimensionallyprinted article in a stationary planar bed, wherein the printing nozzleor nozzles move vertically to accommodate the addition of each layer ofsolid particles. However, a three-dimensionally printed article can beproduced in a moveable planar bed configured for vertical movementrelative to a printing nozzle. FIGS. 3A-3D show a process for producingan article by three-dimensional printing with a moveable planar bed 112.Referring to FIG. 1A, a layer of solid particles 110 is positioned inthe planar bed 112 over a vertically-moveable platform 115 in acontainer 114. The vertical movement of the platform 115 can be actuatedthrough a support member 117. As described above in connection withFIGS. 1A-1D, the layer of solid particles 110 comprises powder or othercollection of particulate materials, which can be present in a loose andfree-flowable form (i e, un-compacted) or in a compacted density. Thelayer of solid particles 110 can be positioned in the planar bed 112 onthe platform 115 in the container 114 using any suitable applicationtechniques and equipment (not shown), such as, for example,pneumatically-operated or gravity-driven powder dispensers, spreadingblades, and/or counter-rotating rollers.

Referring to FIG. 3B, a liquid binder 120 is applied over apredetermined area 123 of the layer of solid particles 110 in the planarbed 112 on the platform 115 in the container 114. The liquid binder 120comprises a 1,1-di-activated vinyl compound, or a multifunctional formthereof, or a combination thereof, as described below. The liquid binder120 infiltrates the gaps between the solid particles in thepredetermined area 123 of the layer of solid particles 110, wets out thesolid particles, and forms a first cross-sectional layer 130 of anarticle. The 1,1-di-activated vinyl compound, or multifunctional formthereof, or combination thereof, in the liquid binder 120 reacts, asdescribed below, and solidifies the liquid binder 120, which bindstogether the solid particles in the first cross-sectional layer 130.

The liquid binder 120 is applied over the predetermined area 123 of thelayer of solid particles 110 using a suitable nozzle 180. The nozzle 180can be computer-controlled and have four translationaldegrees-of-freedom, as indicated at 185—i.e., the nozzle 180 can move inthe X and Y directions parallel to the planar bed 112 to apply theliquid binder 120 in the predetermined area 123 (although not shown, andnot strictly necessary in the implementation illustrated in FIGS. 3A-3D,and the nozzle 180 can optionally move in the vertical directionperpendicular to the planar bed 112 to position the nozzle 180 closer toor farther away from the planar surface of the layer of solid particles110). Although not shown in FIGS. 3B-3C, it is understood thatimplementations of the processes described in this specification canutilize two or more nozzles to apply the liquid binder 120 in thepredetermined area 123 (for example, an inkjet-like print headcomprising multiple nozzles).

A process for producing an article by three-dimensional printing canfurther comprise repeating the powder/particle-positioning, liquidbinder application, infiltration, and reaction steps, as describedabove, a plurality of times to produce a plurality of bondedcross-sectional layers that together comprise the three-dimensionalarticle. Referring to FIG. 3C, the platform 115 is moved downwardly(along the Z-axis, as indicated at 119), which moves the surface of thefirst layer of solid particles 110 and the first cross-sectional layer130 of the three-dimensional article being printed away from the nozzle180. A second layer of solid particles 140 is positioned over the firstlayer of solid particles 110 and over the first cross-sectional layer130 of the article. Additional liquid binder 120 is applied over apredetermined area 125 of the second layer of solid particles 140 in theplanar bed 112 on the platform 115 in the container 114. The liquidbinder 120 comprises a 1,1-di-activated vinyl compound, or amultifunctional form thereof, or a combination thereof, as describedbelow. The liquid binder 120 infiltrates the gaps between the solidparticles in the predetermined area 125 of the second layer of solidparticles 140, wets out the solid particles, and forms a secondcross-sectional layer 150 of the article. The second cross-sectionallayer 150 is located over and in physical contact with the firstcross-sectional layer 130 of the article. The 1,1-di-activated vinylcompound, or multifunctional form thereof, or combination thereof, inthe liquid binder 120 reacts, as described below, and solidifies theliquid binder 120, which binds together the solid particles in thesecond cross-sectional layer 150, and also binds together the firstcross-sectional layer 130 and the second cross-sectional layer 150.

Referring to FIG. 3D, platform 115 is again moved downwardly (along theZ-axis, as indicated at 119), which moves the surface of the secondlayer of solid particles 140 and the second cross-sectional layer 150 ofthe three-dimensional article being printed away from the nozzle 180. Athird layer of solid particles 160 is positioned over the second layerof solid particles 140 and over the second cross-sectional layer 150 ofthe article. Additional liquid binder 120 is applied over apredetermined area 127 of the third layer of solid particles 160 in theplanar bed 112 on the platform 115 in the container 114. The liquidbinder 120 comprises a 1,1-di-activated vinyl compound, or amultifunctional form thereof, or a combination thereof, as describedbelow. The liquid binder 120 infiltrates the gaps between the solidparticles in the predetermined area 127 of the third layer of solidparticles 160, wets out the solid particles, and forms a thirdcross-sectional layer 170 of the article. The third cross-sectionallayer 170 is located over and in physical contact with the secondcross-sectional layer 150 of the article. The 1,1-di-activated vinylcompound, or multifunctional form thereof, or combination thereof, inthe liquid binder 120 reacts, as described below, and solidifies theliquid binder 120, which binds together the solid particles in the thirdcross-sectional layer 170, and also binds together the secondcross-sectional layer 150 and the third cross-sectional layer 170. Theprocess illustrated in FIGS. 3A-3D produces a three-dimensionallyprinted article that is analogous to the article 90 described inconnection with FIGS. 2A and 2B.

As described above, the liquid binder comprises a 1,1-di-activated vinylcompound, or multifunctional form thereof, or combination thereof. The1,1-di-activated vinyl compound can comprise methylene dicarbonylcompounds, dihalo vinyl compounds, dihaloalkyl disubstituted vinylcompounds, or cyanoacrylate compounds, or multifunctional forms of anythereof, or combinations of any thereof. Examples of 1,1-di-activatedvinyl compounds and multifunctional forms thereof that can be used toformulate the liquid binder are described in U.S. Pat. Nos. 8,609,885;8,884,051; 9,108,914; 9,181,365; and 9,221,739, which are incorporatedby reference into this specification. Additional examples of1,1-di-activated vinyl compounds and multifunctional forms thereof thatcan be used to formulate the liquid binder are described in U.S.Publication Nos. 2014/0288230; 2014/0329980; and 2016/0068618, which areincorporated by reference into this specification.

The liquid binder can be formulated with a 1,1-di-activated vinylcompound comprising a methylene malonate. Methylene malonates arecompounds having the general formula (I):

wherein R and R can be the same or different and can represent nearlyany substituent or side-chain, such as substituted or unsubstitutedalkyl or aryl groups. For example, the liquid binder can be formulatedwith a dialkyl methylene malonate, a diaryl methylene malonate, amultifunctional form of a dialkyl methylene malonate, or amultifunctional form of a diaryl methylene malonate, or a combination ofany thereof.

A multifunctional form of a methylene malonate can comprise atransesterification adduct of the methylene malonate and a polyol. Amultifunctional form of a methylene malonate can thus have the generalformula (II):

wherein X is a polyol residue and each R may be the same or different,as described above. As used herein the term “residue” refers to a groupderived from the respective compound. For instance, in the aboveformula, X is an n-valent group derived from a polyol by atransesterification reaction involving methylene malonate and n hydroxylgroups of said polyol. Likewise, a polymer comprising residues of acertain compound is obtained from polymerizing said compound. In someexamples, a multifunctional form of a methylene malonate can comprise atransesterification adduct of the methylene malonate and a diol, andthus have the general formula (III):

wherein X is a diol residue and R and R′ can be the same or different,as described above.

Polyols that are suitable for the production of a transesterificationadduct with a methylene malonate include, for example, polymeric polyols(such as polyether polyols, polyester polyols, acrylic polyols, andpolycarbonate polyols) and monomeric polyols (such as alkane polyols,including alkane diols such as 1,5-pentanediol and 1,6-hexanediol). Thetransesterification adduct can be formed by the reaction of a methylenemalonate and a polyol, in the presence of a catalyst, in a suitablereaction medium. Examples of transesterification adducts of methylenemalonates and polyols that may be used in the coating compositions aredescribed in U.S. Publication No. 2014/0329980 and U.S. Pat. No.9,416,091, which are incorporated by reference herein. Further, theconcentration of the transesterification adduct can be influenced byratio of the reactants and/or distillation or evaporation of thereaction medium.

The liquid binder can be formulated with dimethyl methylene malonate(D3M), a multifunctional form of D3M, or both. The liquid binder can beformulated with diethyl methylene malonate (DEMM), a multifunctionalform of DEMM, or both. The multifunctional forms of D3M or DEMM cancomprise transesterification adducts of D3M or DEMM and a polyol, suchas, for example, 1,5-pentanediol or 1,6-hexanediol.

The liquid binder can be formulated with a combination of a dialkylmethylene malonate and a multifunctional form of a dialkyl methylenemalonate. The liquid binder can be formulated with, for example, DEMMand a multifunctional form of DEMM comprising a transesterificationadduct of DEMM and at least one polyol. The DEMM can be transesterifiedwith polyol comprising, for example, an alkane diol such as1,5-pentanediol or 1,6-hexanediol.

1,1-Di-activated vinyl compounds, including multifunctional formsthereof, anionically polymerize through the vinyl functionality in themolecules and produce polymers having carbon-carbon backbone chains.Binders comprising multifunctional forms of 1,1-di-activated vinylcompounds will anionically polymerize through the multiple vinylfunctionality in the molecules and form cross-linked thermoset polymersnetworks having carbon-carbon backbone chains covalently linked togetherthrough crosslinking groups provided from the linking groups in themultifunctional 1,1-di-activated vinyl compound molecules. Withoutintending to be limited by any theory, it is believed that1,1-di-activated vinyl compounds, including multifunctional formsthereof, spontaneously polymerize under alkaline conditions. Thus, whenthe gaps between solid particles are infiltrated with a liquid bindercomprising a 1,1-di-activated vinyl compound, or a multifunctional formthereof, or a combination thereof, the 1,1-di-activated vinyl compoundsreact by polymerizing, which solidifies and hardens the liquid binder,binds the solid particles together, and binds constituentcross-sectional layers to adjacent cross-sectional layers in athree-dimensional printed article.

The surface chemistry of the solid particles can be sufficientlyalkaline that polymerization of 1,1-di-activated vinyl compounds occursspontaneously upon contact of the liquid binder and the solid particles.For example, glass materials such as soda-lime glass (A-glass) andborosilicate glass (E-glass) are relatively alkaline materials and, assuch, glass particles (e.g., solid glass microspheres) willspontaneously initiate the polymerization of 1,1-di-activated vinylcompounds upon contact. However, the surface chemistry of the solidparticles may be insufficiently alkaline to spontaneously initiatepolymerization, and an activator compound can be applied (e.g., sprayedor otherwise deposited) over at least a portion of the cross-sectionallayers formed after the applied liquid binder infiltrates between thesolid particles to activate the polymerization reaction. Alternatively,or in addition, the solid particles can be surface treated with anactivator compound before using the solid particles in athree-dimensional printing process.

As used in this specification, the term “activator” means a compound orother agent capable of initiating and/or catalyzing polymerization of1,1-di-activated vinyl compounds or multifunctional forms thereof. Theterm “activator” includes (1) active forms of activator compounds and(2) latent precursor forms of activator compounds that are capable ofconversion from the latent precursor form into the active form (e.g., byexposure to an effective amount of heat, electromagnetic radiation,pressure, or a chemical co-activator). Additionally, latent precursorforms of activator compounds that are capable of conversion into theactive form include activators associated with a volatile or otherwiseremovable neutralizing agent or inhibitor compound that can evaporate orotherwise be removed from an activator compound when applied over across-sectional layer, thereby activating the activator.

The activator can comprise a base. As used in this specification, theterm “base” means an electronegative compound or functional groupcapable of initiating the anionic polymerization of a 1,1-di-activatedvinyl compound. Suitable activators include organic bases (e.g.,amine-containing compounds and carboxylate salts), inorganic bases(e.g., hydroxide salts, carbonate salts, and metal oxides),organometallic compounds, and combinations of any thereof. Suitableactivators also include polymers comprising pendant and/or terminalamine, carboxylate salt, or other base functionality capable ofinitiating the anionic polymerization of a 1,1-di-activated vinylcompound.

The activator can comprise a strong base (pH over 9), a moderate base(pH from 8-9), or a weak base (pH from over 7 to 8), or a combination ofany thereof. The activator can comprise, for example, sodium acetate;potassium acetate; acid salts of sodium, potassium, lithium, copper, orcobalt; tetrabutyl ammonium fluoride, chloride, or hydroxide; an amine,including primary, secondary, and tertiary amines; an amide; salts ofpolymer bound acids; benzoate salts; 2,4-pentanedionate salts; sorbatesalts; propionate salts; secondary aliphatic amines; piperidene,piperazine, N-methylpiperazine, dibutylamine, morpholine, diethylamine,pyridine, triethylamine, tripropylamine, triethylenediamine,N,N-dimethylpiperazine, butylamine, pentylamine, hexylamine,heptylamine, nonylamine, decylamine; 1,4-diazabicyclo[2.2.2]octane(DABCO); 1,1′-iminobis-2-propanol (DIPA); 1,2-cyclohexanediamine;1,3-cyclohexandimethanamine; 2-methylpentamethylenediamine;3,3-iminodipropylamine; triacetone diamine (TAD); salts of amines withorganic monocarboxylic acids; piperidine acetate; metal salt of a lowermonocarboxylic acid; copper(II) acetate, cupric acetate monohydrate,zinc acetate, zinc chloracetate, magnesium chloracetate, magnesiumacetate; salts of acid containing polymers; salts of polyacrylic acidco-polymers; and combinations of any thereof.

An activator compound can comprise a tertiary amine compound such as,for example, DABCO; 2-(dimethylamino)ethanol (DMAE/DMEA);2-piperazin-1-ylethylamine;N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine;2-[2-(dimethylamino)ethoxy]ethanol;1-[bis[3-(dimethylamino)propyl]amino]-2-propanol;N,N,N′,N″,N″-pentamethyldiethylenetriamine;N,N,N′,N′-tetraethyl-1,3-propanediamine;N,N,N′,N′-tetramethyl-1,4-butanediamine;N,N,N′,N′-tetramethyl-1,6-hexanediamine;1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane;1,3,5-trimethylhexahydro-1,3,5-triazine; methyl dicocoamine;1,8-diazabicycloundec-7-ene (DBU); 1,5-diazabicyclo-[4,3,0]-non-5-ene(DBN); 1,1,3,3-tetramethylguanidine;1,5,7-triazabicyclo[4.4.0]dec-5-ene;7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; or combinations of anythereof. A tertiary amine activator can comprise a bicyclic guanidinecompound or a substituted derivative thereof, such as, for example,1,5,7-triazabicyclo[4.4.0]dec-5-ene; or7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, or a substitutedderivative of either thereof, or a combination of any thereof.

An activator compound can comprise an aminosilane compound. Aminosilanecompounds have an amine group and a silane group covalently bonded inthe same molecule. Examples of suitable aminosilane compounds includetrialkoxysilanes such as 3-aminopropyltriethoxysilane. The solidparticles can be surface treated by contacting the solid particles withan activator compound, such as an aminosilane compound or other aminecompound, for example, and then using the pre-treated solid particles ina three-dimensional printing process. The activator compound canchemically and/or physically adsorb onto the surfaces of the solidparticles, for example, to increase the alkalinity of the particles'surface chemistry.

Additional examples of activators and activation methods that can beused in connection with the present invention are described in U.S. Pat.No. 9,181,365, which is incorporated by reference into thisspecification.

As used in this specification, the terms “solid particles,” “powder,”“particulate material,” and the like, are generally synonymous and meana free-flowable accumulation of discrete pieces of solid-state material.Generally, the size of the solid particles is limited by the thicknessof the constituent cross-sectional layers to be printed—i.e., theparticles are preferably approximately smaller than the thickness of thelayers to be printed. The solid particles can have any regular orirregular shape. Using smaller solid particles can provide advantagessuch as smaller feature size, the ability to use thinner layers, and theability to reduce what is known in the art of three-dimensional printingas a “stair stepping” effect. The solid particles can have a meanparticle size, determined using microscopic image analysis, ranging from1 μm to 500 μm, or any sub-range subsumed therein, such as, for example,5-250 μm, 10-300 μm, 10-100 μm, or 10-50 μm.

The solid particles can comprise organic particles (i.e., particlescomprising organic material such as carbon-based plastics, bio-derivedmaterials, or predominantly carbon material (e.g., carbon black,graphite, graphene, carbon nanotubes, and the like)) or inorganicparticles (i.e., particles comprising inorganic materials such asmetals, alloys, glasses, ceramics, minerals, and the like), or acombination of any thereof.

The solid particles can comprise thermoplastic or other polymerparticles. Examples of polymers particles include particles comprisingthermoplastic materials such as poly(methyl methacrylate), polystyrene,polyamides, polyesters, polyethylene, polypropylene, polyurethanes,polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone,poly(ethylene terephthalate), styrene-acrylonitrile copolymer, anepoxy-based polymer, polyethers, polyamines, polyacids, polycarbonates,and polysiloxanes.

The solid particles can comprise inorganic particles, which can compriseany inorganic material in particulate form, such as, for example, metalparticles, alloy particles, metal oxide particles, or glass particles.The solid particles can comprise metal or alloy particles such asparticles comprising iron or iron-base alloys (e.g., steels), titaniumor titanium-base alloys, or aluminum or aluminum-base alloys. The solidparticles can comprise metal oxide particles such as particlescomprising titanium dioxide, zirconium dioxide, zinc oxide, silicondioxide (silica), magnesium oxide, an iron oxide (e.g., iron(III) oxide(Fe₂O₃)-based pigments), a chromium oxide (e.g., chromium(III) oxide(Cr₂O₃)-based particles), or particles comprising an aluminum oxide(e.g., alumina (Al₂O₃)-based particles), or a combination of anythereof. The solid particles can comprise titanium dioxide, zirconiumdioxide, zinc oxide, magnesium oxide, an iron oxide, a chromium oxide,silicon dioxide (silica), an aluminum oxide (alumina), or a glass, or acombination of any thereof.

The solid particles can comprise glass particles and/or silicaparticles. Examples of suitable glass particles include solid glassmicrospheres (e.g., Spheriglass® products, available from PottersIndustries LLC, Valley Forge, Pa., USA). The solid particles cancomprise mixtures of different particles, such as, for example, mixturescomprising glass particles and metal oxide particles.

The solid particles can also comprise a particle composition comprisingcore particles comprising a functionalizing layer over at least aportion of the outer surface of the core particles, wherein thefunctionalizing layer comprises a reaction product of a 1,1-di-activatedvinyl compound, or a multifunctional form thereof, or a combinationthereof. Such particle compositions are described, for example, in aco-pending provisional patent application filed on the same date as thepresent application entitled “PARTICLES HAVING SURFACES FUNCTIONALIZEDWITH 1,1-DI-ACTIVATED VINYL COMPOUNDS,” and corresponding to AttorneyDocket No. 16011114V1, which is incorporated by reference into thisspecification.

The three-dimensional articles produced by the processes described inthis specification comprise a plurality of cross-sectional layers bondedtogether, wherein each cross-sectional layer comprises a solid bindercomprising a reaction product of a 1,1-di-activated vinyl compound, or amultifunctional form thereof, or a combination thereof, and a pluralityof solid particles embedded in the solid binder. The three-dimensionalarticles can be further processed, for example, to produce a sintered orotherwise fused article. In one example, the process can produce athree-dimensional article comprising thermoplastic particles embedded inthe solid binder, and the article can be heat treated to sinter or fusethe thermoplastic particles together. In another example, the processcan produce a three-dimensional article comprising metal and/or alloyparticles embedded in the solid binder, and the article can be heattreated to sinter the metal and/or alloy particles together, optionallywith pyrolysis or other removal of the solid binder from the sinteredarticle.

WORKING EXAMPLES

The following working examples are intended to further describe theinvention. It is understood that the invention described in thisspecification is not necessarily limited to the examples described inthis section.

Example 1

A layer of soda-lime glass microspheres pretreated with an aminosilanecoupling agent (Spheriglass® 3000 CP-03, commercially available fromPotters Industries LLC, Valley Forge, Pa., USA) was positioned to form aplanar bed. A liquid binder was applied over the layer of glassmicrospheres using a syringe (5 milliliters of diethyl methylenemalonate—DEMM). The applied DEMM binder infiltrated into the layer andwet out the glass microspheres. The DEMM binder polymerized upon contactwith the glass microspheres, solidified within 20-30 seconds, and formeda first layer comprising the glass microspheres embedded within thesolidified DEMM binder.

A second layer of the glass microspheres (2 grams) was positioned overthe first layer comprising the glass microspheres embedded within thesolidified DEMM binder. Additional liquid DEMM binder (5 milliliters)was applied over the layer of glass microspheres using a syringe. Theapplied DEMM binder infiltrated into and wet out the second layer ofglass microspheres. The DEMM binder polymerized upon contact with theglass microspheres, solidified within 20-30 seconds, and formed a secondlayer comprising the glass microspheres embedded within the solidifiedDEMM binder. The polymerization of the DEMM also bonded together thefirst and second layers comprising the glass microspheres embeddedwithin the solidified DEMM binder.

The above-described lay-up procedure was repeated two additional timesto produce a prototype three-dimensional article comprising fourcross-sectional layers bonded together, each cross-sectional layercomprising a solid binder comprising a polymerization reaction productof DEMM and glass microspheres embedded within the solid binder. Thefour constituent layers built-up a monolithic and integralthree-dimensional article.

Example 2

A layer of boro-silicate glass microspheres was positioned to form aplanar bed (2 grams of Spheriglass® 3000E, available from PottersIndustries LLC, Valley Forge, Pa., USA). A liquid binder was appliedover the layer of glass microspheres using a syringe (5 millilitersDEMM). The applied DEMM binder infiltrated into the layer and wet outthe glass microspheres. The DEMM binder polymerized upon contact withthe glass microspheres, solidified within 20-30 seconds, and formed alayer comprising the glass microspheres embedded within the solidifiedDEMM binder.

Example 3

An amorphous precipitated silica powder pre-treated with an aminosilanecoupling agent was prepared as follows. 300 parts-by-weight of silicapowder (Lo-Vel 27, available from PPG Industries, Inc., Pittsburgh, Pa.,USA) were mixed with 30 parts-by-weight of 3-aminopropyltriethoxysilane(Silquest A1100, available from Momentive Performance Materials Inc.)and 70 parts-by-weight of n-butyl acetate in a V-blender equipped withan intensifier bar. The components were added over 3 minutes and thenallowed to mix for an additional 3-5 minutes. The mixture was thenheated overnight in an oven operating at 85° C.

A layer of the aminosilane-treated silica particles (2 grams) waspositioned to form a planar bed. A liquid binder was applied over thelayer of silica using a syringe (5 milliliters DEMM). The applied DEMMbinder infiltrated into the layer and wet out the silica particles. TheDEMM binder polymerized over approximately 1.5 hours and formed a layercomprising the silica particles embedded within the solidified DEMMbinder.

As second layer of the aminosilane-treated silica particles (2 grams)was positioned over the first layer comprising silica particles embeddedwithin the solidified DEMM binder. Additional liquid DEMM binder (5milliliters) was applied over the layer of silica particles using asyringe. The applied DEMM binder infiltrated into and wet out the secondlayer of glass microspheres. The applied DEMM binder infiltrated intothe layer and wet out the silica particles. The DEMM binder polymerizedover approximately 1.5 hours and formed a layer comprising the silicaparticles embedded within the solidified DEMM binder. The polymerizationof the DENIM also bonded together the first and second layers comprisingthe silica particles embedded within the solidified DEMM binder.

This procedure produced a prototype three-dimensional article comprisingtwo cross-sectional layers bonded together, each cross-sectional layercomprising a solid binder comprising a polymerization reaction productof DEMM and silica particles embedded within the solid binder. The twoconstituent layers built-up a monolithic and integral three-dimensionalarticle.

Example 4

A layer of amorphous precipitated silica powder (2 grams of Lo-Vel 27,available from PPG Industries, Inc., Pittsburgh, Pa., USA) waspositioned to form a planar bed. A liquid binder was applied over thelayer of silica using a syringe (5 milliliters DEMM). The applied DENIMbinder infiltrated into the layer and wet out the silica particles. TheDEMM binder did not polymerize. Without intending to be bound by anytheory, it is believed that the relatively acidic surface chemistry ofthe silica particles (pH of approximately 6.5-7.3 in water) was unableto initiate anionic polymerization through the vinyl functionality inthe DEMM molecules. In contrast, in Example 3, the amine functionalityin the 3-aminopropyl-triethoxysilane was believed to be sufficientlyalkaline to initiate anionic polymerization of the DEMM binder.

Aspects of the Invention

Aspects of the invention include, but are not limited to, the followingnumbered clauses.

-   1. A process for producing an article by three-dimensional printing,    the process comprising:

positioning a layer of solid particles in a planar bed;

applying a liquid binder over a predetermined area of the layer of solidparticles, the liquid binder comprising a 1,1-di-activated vinylcompound, or a multifunctional form thereof, or a combination thereof;

infiltrating gaps between the solid particles with the liquid binder inthe predetermined area of the layer of solid particles to form a firstcross-sectional layer of an article; and reacting the 1,1-di-activatedvinyl compound, or multifunctional form thereof, or combination thereof,thereby solidifying the liquid binder and binding the solid particles inthe first cross-sectional layer of the article.

-   2. The process of clause 1, further comprising:

(i) positioning a second layer of solid particles in the planar bed overthe first cross-sectional layer of the article;

(ii) applying additional liquid binder over a predetermined area of thesecond layer of solid particles, the liquid binder comprising the1,1-di-activated vinyl compound, or multifunctional form thereof, orcombination thereof;

(iii) infiltrating the solid particles with the additional liquid binderin the predetermined area of the second layer of solid particles to forma second cross-sectional layer of the article, wherein the secondcross-sectional layer of the article is located over and in physicalcontact with the first cross-sectional layer of the article; and

(iv) reacting the 1,1-di-activated vinyl compound, or multifunctionalform thereof, or combination thereof, thereby solidifying the liquidbinder and binding the solid particles in the second cross-sectionallayer of the article, and binding together the first and secondcross-sectional layers of the article.

-   3. The process of clause 2, wherein steps (i)-(iv) are repeated a    plurality of times to produce a plurality of bonded cross-sectional    layers that together comprise the article.-   4. The process of any one of clauses 1-3, wherein reacting the    1,1-di-activated vinyl compound, or multifunctional form thereof, or    combination thereof, comprises polymerizing the 1,1-di-activated    vinyl compound, or multifunctional form thereof, or combination    thereof.-   5. The process of clause 4, wherein the polymerization occurs    spontaneously upon contact of the liquid binder and the solid    particles.-   6. The process of any one of clauses 1-5, wherein reacting the    1,1-di-activated vinyl compound, or multifunctional form thereof, or    combination thereof, comprises applying an activator compound over    at least a portion of the first cross-sectional layer of the    article.-   7. The process of clause 6, wherein the activator compound comprises    a tertiary amine compound.-   8. The process of clause 6 or clause 7, wherein the activator    compound comprises 1,4-diazabicyclo[2.2.2] octane.-   9. The process of clauses 6-8, wherein the activator compound    activates polymerization of the 1,1-di-activated vinyl compound, or    multifunctional form thereof, or combination thereof.-   10. The process of any one of clauses 1-9, wherein the solid    particles comprise an activator compound chemically and/or    physically adsorbed onto surfaces of the solid particles.-   11. The process of clause 6-10, wherein the activator compound    comprises an amine compound.-   12. The process of clause 10 or clause 11, wherein the activator    compound comprises an aminosilane compound.-   13. The process of any one of clauses 6-12, wherein the activator    compound activates polymerization of the 1,1-di-activated vinyl    compound, or multifunctional form thereof, or combination thereof.-   14. The process of any one of clauses 1-13, wherein the solid    particles comprise inorganic particles.-   15. The process of any one of clauses 1-14, wherein the solid    particles comprise titanium dioxide, zirconium dioxide, zinc oxide,    magnesium oxide, an iron oxide, a chromium oxide, silicon dioxide,    an aluminum oxide, a metal, an alloy, or a glass, or a combination    of any thereof.-   16. The process of any one of clauses 1-15, wherein the solid    particles comprise glass particles.-   17. The process of any one of clauses 1-16, wherein the solid    particles comprise silica.-   18. The process of any one of clauses 1-17, wherein the solid    particles comprise organic particles.-   19. The process of any one of clauses 1-18, wherein the solid    particles comprise thermoplastic particles.-   20. The process of any one of clauses 1-19, wherein the    1,1-di-activated vinyl compound comprises a methylene dicarbonyl    compound, a dihalo vinyl compound, a dihaloalkyl disubstituted vinyl    compound, or a cyanoacrylate compound, or a multifunctional form of    any thereof, or a combination of any thereof.-   21 The process of any one of clauses 1-20, wherein the    1,1-di-activated vinyl compound comprises:

a dialkyl methylene malonate;

a diaryl methylene malonate;

a multifunctional form of a dialkyl methylene malonate; or

a multifunctional form of a diaryl methylene malonate; or

a combination of any thereof.

-   22. The process any one of clauses 1-21, wherein the    1,1-di-activated vinyl compound comprises:

diethyl methylene malonate;

a multifunctional form of diethyl methylene malonate comprising atransesterification adduct of diethyl methylene malonate and at leastone polyol;

dimethyl methylene malonate; or

a multifunctional form of dimethyl methylene malonate comprising atransesterification adduct of dimethyl methylene malonate and at leastone polyol; or

a combination of any thereof.

-   23. The process any one of clauses 1-22, wherein the    1,1-di-activated vinyl compound comprises a transesterification    adduct of diethyl methylene malonate and a diol.-   24. The process clause 23, wherein the diol comprises an alkane    diol.-   25. The process clause 24, wherein the alkane diol comprises    1,5-pentane diol and/or 1,6-hexanediol.-   26. A three-dimensional article comprising:

a plurality of cross-sectional layers bonded together, eachcross-sectional layer comprising:

a solid binder comprising a reaction product of a 1,1-di-activated vinylcompound, or a multifunctional form thereof, or a combination thereof;and

a plurality of solid particles in the solid binder.

-   27. The three-dimensional article of clause 26, wherein the solid    binder comprises a polymerization reaction product of the    1,1-di-activated vinyl compound, or multifunctional form thereof, or    combination thereof.-   28. The three-dimensional article of clause 26 or clause 27, wherein    the solid particles comprise inorganic particles.-   29. The three-dimensional article of any one of clauses 26-28,    wherein the solid particles comprise titanium dioxide, zirconium    dioxide, zinc oxide, magnesium oxide, an iron oxide, a chromium    oxide, silicon dioxide, an aluminum oxide, a metal, an alloy, or a    glass, or a combination of any thereof-   30. The three-dimensional article of any one of clauses 26-29,    wherein the solid particles comprise glass particles.-   31. The three-dimensional article of any one of clauses 26-30,    wherein the solid particles comprise silica.-   32. The three-dimensional article of any one of clauses 26-31,    wherein the solid particles comprise organic particles.-   33. The three-dimensional article of any one of clauses 26-32,    wherein the solid particles comprise thermoplastic particles.-   34. The three-dimensional article of any one of clauses 26-33,    wherein the solid particles comprise an activator compound    chemically and/or physically adsorbed onto surfaces of the solid    particles.-   35. The three-dimensional article of clause 34, wherein the    activator compound comprises an amine compound.-   36. The three-dimensional article of clause 34 or clause 35, wherein    the activator compound comprises an aminosilane compound.-   37 The three-dimensional article of any one of clauses 26-36,    wherein the 1,1-di-activated vinyl compound comprises a methylene    dicarbonyl compound, a dihalo vinyl compound, a dihaloalkyl    disubstituted vinyl compound, or a cyanoacrylate compound, or a    multifunctional form of any thereof, or a combination of any    thereof.-   38. The three-dimensional article of any one of clauses 26-37,    wherein the 1,1-di-activated vinyl compound comprises:

a dialkyl methylene malonate;

a diaryl methylene malonate;

a multifunctional form of a di alkyl methylene malonate; or

a multifunctional form of a diaryl methylene malonate; or

a combination of any thereof.

-   39. The three-dimensional article of any one of clauses 26-38,    wherein the 1,1-di-activated vinyl compound comprises:

diethyl methylene malonate;

a multifunctional form of diethyl methylene malonate comprising atransesterification adduct of diethyl methylene malonate and at leastone polyol;

dimethyl methylene malonate; or

a multifunctional form of dimethyl methylene malonate comprising atransesterification adduct of dimethyl methylene malonate and at leastone polyol; or

a combination of any thereof.

-   40. The three-dimensional article of any one of clauses 26-39,    wherein the 1,1-di-activated vinyl compound comprises a    transesterification adduct of diethyl methylene malonate and a diol.-   41. The three-dimensional article of clause 40, wherein the diol    comprises an alkane diol.-   42. The three-dimensional article of clause 41, wherein the alkane    diol comprises 1,5-pentane diol and/or 1,6-hexanediol.-   43. The three-dimensional article of any of clauses 26-42 obtained    by a process according to any of clauses 1-25.-   44. Use of a 1,1-di-activated vinyl compound, or a multifunctional    form thereof, or a combination thereof as described in any of    clauses 20-25 or 37-43 as a binder in three-dimensional printing.-   45. The use of clause 44 wherein the three-dimensional printing is    carried out using the process of any of clauses 1-25 to produce the    three-dimensional article of any of clauses 26-43.

Various features and characteristics are described in this specificationto provide an understanding of the composition, structure, production,function, and/or operation of the invention, which includes theprocesses and articles. It is understood that the various features andcharacteristics of the invention described in this specification can becombined in any suitable manner, regardless of whether such features andcharacteristics are expressly described in combination in thisspecification. The Inventors and the Applicant expressly intend suchcombinations of features and characteristics to be included within thescope of the invention described in this specification. As such, theclaims can be amended to recite, in any combination, any features andcharacteristics expressly or inherently described in, or otherwiseexpressly or inherently supported by, this specification. Furthermore,the Applicant reserves the right to amend the claims to affirmativelydisclaim features and characteristics that may be present in the priorart, even if those features and characteristics are not expresslydescribed in this specification. Therefore, any such amendments will notadd new matter to the specification or claims, and will comply withwritten description, sufficiency of description, and added matterrequirements, including the requirements under 35 U.S.C. § 112(a) andArticle 123(2) EPC.

Any numerical range recited in this specification describes allsub-ranges of the same numerical precision (i.e., having the same numberof specified digits) subsumed within the recited range. For example, arecited range of “1.0 to 10.0” describes all sub-ranges between (andincluding) the recited minimum value of 1.0 and the recited maximumvalue of 10.0, such as, for example, “2.4 to 7.6,” even if the range of“2.4 to 7.6” is not expressly recited in the text of the specification.Accordingly, the Applicant reserves the right to amend thisspecification, including the claims, to expressly recite any sub-rangeof the same numerical precision subsumed within the ranges expresslyrecited in this specification. All such ranges are inherently describedin this specification such that amending to expressly recite any suchsub-ranges will comply with written description, sufficiency ofdescription, and added matter requirements, including the requirementsunder 35 U.S.C. § 112(a) and Article 123(2) EPC. Also, unless expresslyspecified or otherwise required by context, all numerical parametersdescribed in this specification (such as those expressing values,ranges, amounts, percentages, and the like) may be read as if prefacedby the word “about,” even if the word “about” does not expressly appearbefore a number. Additionally, numerical parameters described in thisspecification should be construed in light of the number of reportedsignificant digits, numerical precision, and by applying ordinaryrounding techniques. It is also understood that numerical parametersdescribed in this specification will necessarily possess the inherentvariability characteristic of the underlying measurement techniques usedto determine the numerical value of the parameter.

The invention(s) described in this specification can comprise, consistof, or consist essentially of the various features and characteristicsdescribed in this specification. The terms “comprise” (and any form ofcomprise, such as “comprises” and “comprising”), “have” (and any form ofhave, such as “has” and “having”), “include” (and any form of include,such as “includes” and “including”), and “contain” (and any form ofcontain, such as “contains” and “containing”) are open-ended linkingverbs. Thus, a composition, coating, or process that “comprises,” “has,”“includes,” or “contains” one or more features and/or characteristicspossesses those one or more features and/or characteristics, but is notlimited to possessing only those one or more features and/orcharacteristics. Likewise, an element of a composition, coating, orprocess that “comprises,” “has,” “includes,” or “contains” one or morefeatures and/or characteristics possesses those one or more featuresand/or characteristics, but is not limited to possessing only those oneor more features and/or characteristics, and can possess additionalfeatures and/or characteristics.

The grammatical articles “a,” “an,” and “the,” as used in thisspecification, including the claims, are intended to include “at leastone” or “one or more”, unless otherwise indicated. Thus, the articlesare used in this specification to refer to one or more than one (i.e.,to “at least one”) of the grammatical objects of the article. By way ofexample, “a component” means one or more components, and thus, possibly,more than one component is contemplated and can be employed or used inan implementation of the described compositions, coatings, andprocesses. Nevertheless, it is understood that use of the terms “at 1east one” or “one or more” in some instances, but not others, will notresult in any interpretation where failure to use the terms limitsobjects of the grammatical articles “a,” “an,” and “the” to just one.Further, the use of a singular noun includes the plural, and the use ofa plural noun includes the singular, unless the context of the usagerequires otherwise.

Any patent, publication, or other document identified in thisspecification is incorporated by reference into this specification inits entirety unless otherwise indicated, but only to the extent that theincorporated material does not conflict with existing descriptions,definitions, statements, illustrations, or other disclosure materialexpressly set forth in this specification. As such, and to the extentnecessary, the express disclosure as set forth in this specificationsupersedes any conflicting material incorporated by reference. Anymaterial, or portion thereof, that is incorporated by reference intothis specification, but which conflicts with existing definitions,statements, or other disclosure material set forth herein, is onlyincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material. Applicantreserves the right to amend this specification to expressly recite anysubject matter, or portion thereof, incorporated by reference. Theamendment of this specification to add such incorporated subject matterwill comply with written description, sufficiency of description, andadded matter requirements, including the requirements under 35 U.S.C. §112(a) and Article 123(2) EPC.

1-25. (canceled)
 26. A three-dimensional article comprising: a plurality of cross-sectional layers bonded together, each cross-sectional layer comprising: a solid binder comprising a reaction product of a 1,1-di-activated vinyl compound, or a multifunctional form thereof, or a combination thereof; and a plurality of solid particles in the solid binder, wherein the solid particles comprise an activator compound chemically and/or physically absorbed onto surfaces of the solid particles.
 27. The three-dimensional article of claim 26, wherein the solid binder comprises a polymerization reaction product of the 1,1-di-activated vinyl compound, or multifunctional form thereof, or combination thereof.
 28. The three-dimensional article of claim 27, wherein the solid particles comprise inorganic particles.
 29. The three-dimensional article of claim 28, wherein the solid particles comprise titanium dioxide, zirconium dioxide, zinc oxide, magnesium oxide, an iron oxide, a chromium oxide, silicon dioxide, an aluminum oxide, a metal, an alloy, or a glass, or a combination of any thereof.
 30. The three-dimensional article of claim 29, wherein the solid particles comprise glass particles.
 31. The three-dimensional article of claim 29, wherein the solid particles comprise silica.
 32. The three-dimensional article of claim 26, wherein the solid particles comprise organic particles.
 33. The three-dimensional article of claim 32, wherein the solid particles comprise thermoplastic particles.
 34. (canceled)
 35. The three-dimensional article of claim 26, wherein the activator compound comprises an amine compound.
 36. The three-dimensional article of claim 35 wherein the activator compound comprises an aminosilane compound.
 37. The three-dimensional article of claim 26, wherein the 1,1-di-activated vinyl compound comprises a methylene dicarbonyl compound, a dihalo vinyl compound, a dihaloalkyl disubstituted vinyl compound, or a cyanoacrylate compound, or a multifunctional form of any thereof, or a combination of any thereof.
 38. The three-dimensional article of claim 37, wherein the 1,1-di-activated vinyl compound comprises: a dialkyl methylene malonate; a diaryl methylene malonate; a multifunctional form of a dialkyl methylene malonate; or a multifunctional form of a diaryl methylene malonate; or a combination of any thereof.
 39. The three-dimensional article of claim 38, wherein the 1,1-di-activated vinyl compound comprises: diethyl methylene malonate; a multifunctional form of diethyl methylene malonate comprising a transesterification adduct of diethyl methylene malonate and at least one polyol; dimethyl methylene malonate; or a multifunctional form of dimethyl methylene malonate comprising a transesterification adduct of dimethyl methylene malonate and at least one polyol; or a combination of any thereof.
 40. The three-dimensional article of claim 39, wherein the 1,1-di-activated vinyl compound comprises a transesterification adduct of diethyl methylene malonate and a diol.
 41. The three-dimensional article of claim 40, wherein the diol comprises an alkane diol.
 42. The three-dimensional article of claim 41, wherein the alkane diol comprises 1,5-pentane diol and/or 1,6-hexanediol.
 43. A three-dimensional article obtained by a process for producing an article by three-dimensional printing, the process comprising: positioning a layer of solid particles in a planar bed, wherein the solid particles comprise an activator compound chemically and/or physically adsorbed onto surfaces of the solid particles; applying a liquid binder over a predetermined area of the layer of solid particles, the liquid binder comprising a 1,1-di-activated vinyl compound, or a multifunctional form thereof, or a combination thereof; infiltrating gaps between the solid particles with the liquid binder in the predetermined area of the layer of solid particles to form a first cross-sectional layer of an article; and reacting the 1,1-di-activated vinyl compound, or multifunctional form thereof, or combination thereof, thereby solidifying the liquid binder and binding the solid particles in the first cross-sectional layer of the article.
 44. A method comprising: producing an article by three-dimensional printing utilizing a 1,1-di-activated vinyl compound, or a multifunctional form thereof, or a combination thereof as a binder in the three-dimensional printing.
 45. The method of claim 44 wherein the three-dimensional printing is carried out using a process for producing an article by three-dimensional printing, the process comprising: positioning a layer of solid particles in a planar bed, wherein the solid particles comprise an activator compound chemically and/or physically adsorbed onto surfaces of the solid particles; applying a liquid binder over a predetermined area of the layer of solid particles, the liquid binder comprising a 1,1-di-activated vinyl compound, or a multifunctional form thereof, or a combination thereof; infiltrating gaps between the solid particles with the liquid binder in the predetermined area of the layer of solid particles to form a first cross-sectional layer of an article; and reacting the 1,1-di-activated vinyl compound, or multifunctional form thereof, or combination thereof, thereby solidifying the liquid binder and binding the solid particles in the first cross-sectional layer of the article wherein the process produces a three-dimensional article comprising a plurality of cross-sectional layers bonded together, each cross-sectional layer comprising: a solid binder comprising a reaction product of a 1,1-di-activated vinyl compound, or a multifunctional form thereof, or a combination thereof; and a plurality of solid particles in the solid binder, wherein the solid particles comprise an activator compound chemically and/or physically absorbed onto surfaces of the solid particles. 